It is known to use clutch bearing units in the automotive applications for actuating a rotating diaphragm of a gearbox from a translating piston of a mechanical, hydraulic or electrical control element. To this end, the clutch bearing unit comprises a clutch rolling bearing with rolling elements, for example balls, a rotatable ring intended to be in contact with diaphragm, and a stationary ring provided with a bore receiving the translating piston. The rings are cut from a sheet metal blank, and then stamped to give their final tubular shape to the race rings, with a toroidal portion defining raceway surfaces for balls.
When a driver operates a clutch pedal, the piston is axially pushed towards the clutch bearing unit. The translating displacement is forwarded to the diaphragm that removes the coupling between the rotating diaphragm connected to the gearbox and a flywheel connected to the vehicle engine. The power torque is not transmitted between the gearbox and the engine, and the operation of clutching or declutching in the gearbox can be achieved. The clutch rolling bearing further adjusts misalignments between diaphragm and piston.
It is known from prior art, for example DE-A1-10 2010 010735, to axially extend the toroidal portion of the rotatable ring with an axial portion, the axial portion being further extended substantially radially by an engagement portion. The engagement portion defines a surface dedicated to come into contact with the diaphragm. The engagement portion is bent in respect with the axial portion and is obtained by stamping of the ring of tubular shape.
The axial portion ensures the rigidity of the rotatable ring for transmitting loads to the diaphragm. The engagement portion defines a large surface for ensuring the contact with the diaphragm even in case of relative axial displacement or sliding of the diaphragm in respect with the clutch rolling bearing.
However, the available space for the clutch rolling bearings in automotive applications tends to be more and more reduced both axially and radially, but with more loads to transmit through the clutch rolling bearing.